Activity.getIntent()是否可以返回null? [英] Can Activity.getIntent() ever return null?

问题描述

Activity.getIntent() 可以返回null吗?

文档中没有提到这种可能性，因此我想知道是否必须在取消引用null值之前检查getIntent()的结果.

The documentation does not mention this as a possibility, so I am wondering if I have to check the result of getIntent() for null value before dereferencing it.

推荐答案

是的，它可以， 但只有两种情况:

Yes, it can, but only in two cases:

在活动构造函数中:
在内部attach方法中设置的意图，从Instrumentation类调用:

In activity constructor:
Intent set up in internal attach method, called from Instrumentation class:

public Activity newActivity(Class<?> clazz, Context context, 
        IBinder token, Application application, Intent intent, ActivityInfo info, 
        CharSequence title, Activity parent, String id,
        Object lastNonConfigurationInstance) throws InstantiationException, 
        IllegalAccessException {
    Activity activity = (Activity)clazz.newInstance();
    ActivityThread aThread = null;
    activity.attach(context, aThread, this, token, 0, application, intent,
            info, title, parent, id,
            (Activity.NonConfigurationInstances)lastNonConfigurationInstance,
            new Configuration(), null, null);
    return activity;
}

因此，意图在构造函数中始终为空.

therefore intent is always null in constructor.

setIntent(null)之后:
可以通过 setIntent()

After setIntent(null):
It's possible to change intent from outside of activity with setIntent().

在所有其他情况下都不能.

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